Piston construction



Aug. 9, 1938. M. Gf FIEDLER 2,126,627

' PISTON CONSTRUCTION Filed April 3, 1957 Patented Aug. 9, 1938 v,UluTaD STATES PATENT OFI-'ics This invention relates to 'pistons lor internal combustion engines, and has for anlmportant object thereof the elimination of the diiliculties ordinarily arising due tounequal expansion of 5- the head and skirt of the piston.

ln the ordinary gasoline engine, the temperature of the piston head ranges between 300 and 500 F., and in the Diesel, or solid 'fuel injection enmne the temperatures are much higher, being ya seldom below 900 F., and often attaining such heat that projecting portions oi the piston are actually burned away.

llt has b'een determined that the heat oi' the piston head is dissipated principally through the la rings due to .the fact that these rings have engagement with portions oi the wall which are comparatively free from oil. As v the rings are ordinarily placed at the upper portion of the piston, this means that the shirt is compara- 20 tively cool, with the result that ii the piston is v made of such diameter including this skirt as to dt the cylinder walls it would tend to bend while the skirt would stillbe comparatively free. This has led to the use of flexible piston skirts in an 35 permit blow-by in operation. ms is particularly Y serious' in solid fuel injection engines whichA necessarily depend upon the creation of relatively high pressures in the cylinder in order toobtain auto-ignition. i0 An important object oi the invention is the provision oi a piston construction in which the axes vof the piston and cylinder will at allv times remain in parallelism, thus insuring against the destructive action on the rings, and in which, at 45 the same time, provision is made for the expansion of the piston head under the relatively high heat to which it is subjected. 'Y

Another object of the invention is the provision in a device of this characterv of a construction 50 such that it may be economically produced and will tend to further reduce the heatextended between the piston proper and the skirt. A

These and Vother objects I attain by the construction shown in the accompanying drawing 56 wherein, for the purpose of illustration, I have it oi the cross head proper. the piston and cross head is established by a lool:-

shown a preferred embodiment of my invention and wherein: Fig. l is a vertical sectional view through a piston constructed'in accordance with my invention showing thev same in position in the cylinn i der;

Fig. 2 is a transverse section on line 2-2 ol Fig. 1; and

Fig. 3 shows a slightly modiiled piston con struction. l E@ Referring now more particularly to the drawing, the numeral I0 generally designates a cylinder, and l l a cross head having a sliding ht in the l cylinder Walls and. having connected thereto Vthe usual connecting rod l2. This cross w head has at its upper end a tubular boss it, the interior of which is in communication with the hollow interior oi the cross head. The numeral ill generally designates a piston, this piston having an axial cavity l5 in its lower end 20 of slightly greater diameter than the boss and seating at its lower end upon the upper surface Connection between ing ring Il engaging in grooves in the confrontat ing side faces of the boss I3 and cavity l5 and iltting therein so that cooking of the piston with relation to the cross` mi? is impossible. The groove I8 in the boss I3 of sufilcient depth to completely accommodate the ring Il and the ring 30 is accessible for complete disposition in this groove to permit removal of the piston from the cross head through radial openings Il in the piston, such openings being preferably Jformed at the base of a ring groove. Piston it is made of au appreclably less diameter than the cross head and the rings 20 employed therein should be equipped with expanders, as more clearly shown .in Fig. 2.

IThe piston itself is so constructed that it will i0 efdclently conduct heat to these rings. in the construction of Fig. 1, this piston comprises a cast iron cap 2| cast upon a body 22 of aluminum, while in the construction shown in Fig. d,

the piston Ha is :l-hollow body formed of any dul heat-conducting material an'd having a plugclosed opening 23 through which sodium. or some other suitable saltmay be introduced to act as a heat-conducting medium.

It will beobvious that in operation, .the cross 5o. y head which, as noted, is relatively elongated, will,

lation to the cross head, but is at all times maintained with its axis in parallelism to that of the cross head, the piston will operate at all times in axial parallelism to the cylinder, floating on its rings 20. Cocking being absolutely prevented, a proper ilt of the cross head may be maintained at all times without regard to the expansion of the piston.

Oily vapors from the engine base will be transmitted through the hollow boss and keep the connection lubricated so that it will at all times be free to move and assume its proper position with relation to the cylinder wall. Additionally, the iioating connection between the piston and cross head serves as an insulation, as there will, at all times, be an oil lm therebetween. This results in relatively low temperatures in the cross head enabling a fit of the same in the cylinder walls to be more closely approximated even though this skirt be made of aluminum or some other relatively highly expansible material.

In some cases a pin 24 extending from the bottom of the piston and engaging in a socket 25 in the upper end Wall of the cross head should be employed to prevent relative rotationof the piston and cross head.

Since the construction is obviously capable of considerable modification without in any manner departing from the spirit of the invention, I do not wish to be understood as limiting myself thereto except as hereinafter claimed.

I claim:

1. A piston and cylinder construction for combustion engines comprising the combination with a cylinder of a cross head having a sliding t therein, a connecting rod connected thereto, a piston of smaller diameter than the cross head and a connection between the piston and cross head constructed and arranged to permit relative vtransaxial displacement and prevent axial displacement of said piston and cross head while maintaining the axes of said piston and cross head in parallel relation.

2. A construction as set forth in claim 1 wherein the cross head has a boss extending into a socket formed in the piston base, the socket and boss having in their confronting side walls grooves coacting to receive-an expansible ring.

3. The construction as set forth in claim l wherein the lpiston is seated upon the cross head and the cross head has a boss extending into a socket formed in the base of the piston, a ring and groove connection between the boss and the confronting wall of the piston socket, the boss being tubular and in communication with the hollow interior of the cross head.

4. The construction as set forth in claim 1 wherein means are provided for conducting crank case vapors to the confronting surfaces of the piston and cross head, thereby insuring lubrication of the same and reducing heat transmission to the cross head.

MAX GEORGE FIEDLER. 

